The present invention is directed to a front chaffer having an inclined closed upstream portion and a declined open downstream portion. A cleaning fan is provided with blade inserts having apertures that limit the transverse slow of air along the cleaning fan blades.
Agricultural combines harvest an agricultural crop, thresh the harvested crop to break the large crop components from the smaller crop components, separate the smaller crop components from the larger crop components, and clean the smaller components to eliminate chaff from the grain. The combine may be equipped with various harvesting assemblies including grain platforms (rigid and flexible), corn headers, row crop headers or windrow pickup platforms depending on the crop and the harvesting practices employed by the farmer. Similarly, the threshing assembly of the combine may be configured in a number of different ways, including a conventional transverse threshing cylinder and concave, or a rotary threshing system that is either axially of transversely arranged. In addition, the separating assembly may comprise conventional straw walkers or rotary assemblies.
The cleaning system removes chaff from the grain. The cleaning system typically comprises a cleaning shoe and a cleaning fan. The smaller crop components from the threshing assembly and the separating assembly are directed to the cleaning shoe. The cleaning shoe typically is provided with a chaffer and a sieve. The chaffer and sieve have transverse louvers that define openings. The heavier clean grain falls through the openings formed by the louvers on the chaffer and the sieve. The air blast from the cleaning fan blows the chaff out the rear of the combine.
There are three types of cleaning shoe actions, they are: reciprocating, shaker and cascading. In a reciprocating shoe the chaffer and sieve move in opposite directions to one another. In a shaker shoe the chaffer and sieve move in the same direction at the same time. In a cascading shoe the chaffers and sieve are positioned so that the small components drop from one unit to another in a cascading or rolling motion.
It is an object of the present invention to provide a high capacity cleaning assembly for an agricultural combine.
A cleaning shoe of an agricultural combine is provided with a front chaffer located upstream from the main chaffer. The front chaffer has a closed upstream portion and an open downstream portion. The closed upstream portion is upwardly inclined and the open downstream portion is downwardly inclined. The front chaffer is oriented so that an air blast from the cleaning fan passes beneath the closed upstream portion and upwardly through the declined open downstream portion. The open downstream portion is provided with transversely extending louvers through which the air blast passes. Grain and heavier particles fall through the louvers to a crash pan that directs these components to a main chaffer.
The cleaning fan is housed in a housing having two air blast openings. The first opening directs a first air blast beneath the front chaffer, the second air blast opening directs a second air blast beneath the crash pan. The cleaning fan comprises a plurality of radially and transversely extending fan blades. The blade inserts forming air dams are located near each transverse end. The blade inserts are provided with apertures that limit the transverse air flow along the blades.